Among the many wondrous things about honey bees, is the fact that they have fewer genes related to detoxifying chemicals than other insects. (1) This fact, combined with the accumulation of pesticides in the environment, and their continued use, results in a serious problem for the bees.
While many, if not most, chemical pesticides are harmful to bees, one class, called the neonicotinoids, are particularly devastating. The neonicotinoids are systemic pesticides, which means they can be applied to plant seeds and grow throughout the entire plant. Systemic pesticides are indiscriminate: insects feeding on any part of the plant will ingest the pesticide. These neonicotinoids are very effective pesticides. They act on an insect’s nervous system causing overstimulation, poisoning and death. (2) There are three chemicals in the neonicotinoid class: clothianidin, imidacloprid and thiamethoxam. These substances are now the most widely used pesticides in the world.
The toxic effect of the neonicotinoids on honey bees was first noticed in Europe in the 1990’s. Beekeepers saw erratic behavior in bees pollinating sunflowers where imidacloprid was used, along with acute losses of bees in the hives. In location after location, increased losses were noted in the year when imidacloprid was introduced. With dramatically declining honey production, and increased colony mortality, France instituted a partial ban on the use of neonicotinoids in 2003,(3) and by 2010, Germany, Italy and Slovenia had followed suit.
In 2010, Henk Tennekes, a Dutch toxicology consultant published: The Systemic Insecticides: A disaster in the making. (4) This book reports the analyses of 26 different surface water samples around the Netherlands. The imidacloprid concentrations ranged from 19 – 4,776 times the acceptable limit of 67 ng/L. No sample was within acceptable limits. These results indicate that imidacloprid builds up in the environment to toxic levels far exceeding the manufacturers safe dosage levels. Tenneke goes on to present considerable evidence on the negative effects of systemic insecticides on insectivorous birds in the Netherlands, highlighting the widespread environmental devastation these substances are causing.
Also in 2010, and consistent with Tenneke’s findings, Wiki-Leaks released an internal EPA memo dated Nov. 2, 2010, stating: “…The proposed use on cotton poses an acute and chronic risk to freshwater and estuarine/marine free-swimming invertebrates…” and “..Clothianidin’s major risk concern is to nontarget insects (that is, honey bees). Clothianidin is a neonicotinoid insecticide that is both persistent and systemic. Acute toxicity studies to honey bees show that clothianidin is highly toxic on both a contact and an oral basis….” (5) The memo goes on to say the original studies showing whole hive effects of clothianidin were acceptable (a study done by the Bayer Corp.) are now deemed deficient and the results considered supplemental. It recommends new research to determine the safety of clothianidin and the other neonicotinoids on honey bees and other land and marine invertebrates, birds and small mammals. But meanwhile, the EPA continues to allow the use of the neonicotinoids, and recommends only a change in labeling and directions for use of the products. In December of 2010, six major groups sent a joint complaint to the EPA about the risk of clothianidin to honey bees and pollinators. (6)
Today, we must await the results of these new studies, and hope they are conducted in a timely manner. Meanwhile, we can all do our part by refraining from the use of any pesticides at all, and spreading the word on the dangers of the neonicotinoids in particular to honey bees and many other species.
There are many factors underlying the massive die off of honey bees around world. Pesticide use is only one of them, but we at the Urban Bee Project believe that even if all other factors were somehow miraculously eliminated, the bees will continue to decline if neonicotinoid pesticides continue to be used.
Here is a list of the brand names neonicotinoids are sold as:
Imidacloprid: Admire, Advantage (flea & tick for dogs), Confidor, Goucho, Marathon, Merit, Premeir, Provado, Bayer Advanced, Rose Defense
Thiamethoxam: Actara, Crusier, Platinum